Method of manufacturing photoelectric tubes



1935- O H. H. GEFFCKEN ET AL 2,012,626

METHOD OF MANUFACTURING PHOTO ELECTRIC TUBES Filed Dec. 6, 1928 H? z'nm'c/z H 56 76/26/2 V and Hans fia/ziiff' Patented Aug. 27, 1935 UNITED STATES ,METHOD OF MANUFACTURING PHOTO- ELECTRIG -TUBES Heinrich HrGeficken and Hans R. Richter, Leipzig, Germany, assignors to Radio Patents Corporation, New York, N. Y., a corporation of New York Application December 6, 1928, Serial No. 324,106

Claims. (o1. 250 27.5)

Our invention relates to the manufacture of photo-electric devices of the kind comprising a sealed bulb which may be of glass, quartz, or other suitable material, containing a film electrode of 5 light sensitive material, such as potassium or sodium, and containing a second electrode for collecting the electrons emitted by the film electrode when the latter is subjected to the influence of light.

It is usual in manufacturing such aphoto-electric tube to apply the film of light sensitive material to a part of the interior surface of the bulb. It has also been suggested to apply the film of light sensitive material to a member arranged in the interior of the tube and consisting of a plate or a rough, meshy net of metal. These means determine the place for the light sensitive material very accurately, and the products achieved by this method are, therefore, very uniform.

Our invention is based on the fact that a fine meshed net of copper, silver or another metal has the property of readily receiving and absorbing the light sensitive material if the latter is placed on it in liquid condition. The fine mesh net acts in the manner of a sponge and, by cohesion and capillary attraction, all of the meshes of the net are coated and filled with a thin layer of photo-electric material. Our invention furnishes a very simple manufacturing method and'produces very sensitive and uniform. tubes.

The invention will best be understood by describing the same with reference to the accompanying single sheet of drawings, in which Figure 1 represents a side elevation of a photoelectric tube in the state of manufacture, the cathode of said tube consisting of a fine meshed net of metal;

Figure 2 represents a top View of the device shown in Figure 1; and

Figure 3 represents a side elevation of a particular type of photo-electric tube, having a circularly arranged film of the light sensitive material, with the center perforated.

Referring to Figures 1 and 2, an anode electrode 2 is arranged in the tube bulb l. The cathode electrode consists of a tight, meshy net 3 of a metal for receiving the photo-electric material in liquid state and attached thereto is the wire 4 which serves as a terminal. During the process of manufacture the tube bulb l is connected to an exhaust pump at 5. The storage bulb 6, which subsequently will be separated from the bulb l by fusing, contains the photo-electric material (potassium, sodium or the like). tric material in the storage bulb 6 will be melted and a large outer diameter.

The photo-clear when the tube bulb is sufiiciently'exhausted and, by tilting the whole device, the liquid will enter into the tube bulb l and upon the net 3. After the net 3 has absorbed in its meshes a suflicient amount of the liquid photo-electric material the device will be tilted again to return excess material into the storage bulb 6.

A particular advantage of our novel method of manufacturing photo-electric tubes resides in the fact that the photo-electric material may be actually applied in a liquid state far from vaporific condition. Consequently, no undesirable precipitation can occur on the smooth, transparent portions of the tube bulb.

After having coated the net 3 with photo-electric material the film thus produced is formed by passing a glow discharge in hydrogen. The hydrogen is finally displaced and suitably replaced by argon, helium, or another inert gas.

The net 3 consists of pure copper, silver, or another suitable metal which readily receives and easily retains the liquid photo-electric material as explained. The anode electrode, on the other hand, is preferably made of a metal (e. g., molybdenum) which does not readily receive and retain the photo-electric material, in order to prevent the accidental adherence of such material to the anode in case the material should splash. It will run off from the anode in such case since the metal employed is not adapted to retain the material.

It is advisable to support the net which is to receive the photo-electric film, with a plate of glass, quartz, iron or other suitable substance, as

. is shown in Figure 3. The net 3 is supported in this figure by means of a plate 1 and is, consequently, fixed in place. The net 3 is of circular shape and perforated in the center, that is to say, it has a ring shape with a small inner diameter A beam of light may pass through the tube in the direction of the arrow 8. A funnel 9 is attached to the plate 1 in order to prevent those parts of the light beam which are diffusedly reflected by the back and front walls of the tube from striking the photoelectric film. The terminals for connecting the Having thus described our invention, what we claim as new and desire to secure by Letters Patcut is:-

1. The process of producing light sensitive electrodes which consists in feeding light sensitive material in a molten state to a metallic fabric support to produce a thin light sensitive film; filling the open spaces of said fabric with the.

device to current are attached to the caps I 0 and M, i g

molten material by cohesion and capillary forces; and removing excess material not absorbed by said fabric.

2. In the art of producing light sensitive electrodes, the step of applying molten light sensitive material to an absorbent metallic surface removing excess material to leave a thin light sensitive film filling the interstices of said surface by adhesive and capillary forces. V

3. A light sensitive electrode comprising a metallic base, a thin metallic net in close contact with said base and a film of light sensitive mate-'- rial held Within the open spaces of saidnet by cohesion and capillary attraction.

4. A light sensitive cathode comprising a finely meshed net, and a mosaic of light sensitive material held entirely within the interstices of said net, the mesh being sufficiently fine to cause the light sensitive material to adhere by adhesive and capillary forces. j v s.

5. The process of producing light sensitive devices'consisting in, applying liquid light sensitive material to a finely meshed net and, removing 'excess material to leave a light sensitive layer filling the. interstices of said net by cohesive and capillary forces.

' HEINRICH H. GEFFCKEN.

ii-IANS R. RICHTER. 

